30 EXPERIMENTAL FARMS 



5 GEORGE v., A. 1915 



value of tlie tubers is but little impaired. The embargo placed upon Canadian 

 potatoes alarmed the growers and shippers who claimed that it would be most difficult 

 to find another market for the potato crop; their fears proved to be ungrounded, 

 however, as the price of potatoes did not drop to any appreciable extent. Towards 

 the end of the year of report, potatoes were almost scarce. 



In order to instruct the farmers, the Division issued two new farmers' circulars : 

 No. 4, entitled 'Potato Diseases transmitted by the use of Unsound Seed Potatoes,' 

 a most useful representation of the most common potato diseases in natural colours, 

 and with a brief and instructive text; and Circular No. 5 on 'Powdery Scab of 

 Potatoes,' which publication briefly treats of this disease which was until recently 

 unsuspected in the Dominion. These two circulars were most widely distributed 

 and instructions by letter and public lectures have enabled this Division to reach 

 many farmers. It is hoped that the persistent efforts to prevent potato diseases from 

 being propagated by the careless use of unsound seed tubers will show good results. 

 In fall and spring the inspection service was directed towards certifying seed 

 potatoes to be free from disease. This will be followed by inspection of the fields 

 and later of the crops, so that this disease should most quickly come under control. 



PLANT PATHOLOGICAL WOKK. 



The work done in this section includes the advice by letter or demonstration on 

 the control of plant diseases already known, and research on a large number of 

 obscure diseases affecting specific vegetation of all kinds. The importance of clear- 

 ing up diseases hitherto little understood must be fully realized. We only need 

 refer to such obscuTe di6e.a6es as ' Little Peach ' and ' Peach Yellows,' the last-named 

 disease being most destructive in the Niagara peninsnla, and about the cause of 

 which absolutely nothing has been discovered since it was first reported in scientific 

 literature. As the disease is at present unknown in tlie western peach orchards of 

 Canada, this appears a sufficient reason for specializing in the investigation of one 

 disease alone. 



There are numerous problems of a physiological nature which have persist)ently 

 defied solution. Of these ' Bitter Pit ' of fruit is one of the most prominent, 

 and is regarded as the most troublesome and economically important fruit disease. 

 Then reference may be made to the perplexing phenomenon ' black heart ' of fruit 

 trees, which is viewed with suspicion by fruit growers, but for which belief, in our 

 opinion, there is no real foundation. In some provinces this trouble is regarded 

 with much concern and accurate information is greatly needed. 



Furthermore, the relation of soil organisms to plant diseases is another problem 

 urgently requiring attention. 



Our experience with common potato scab would indicate that the organism 

 either lives directly in the soil, or its growth is favoured by the chemical condition 

 of the soil, brought about by the use of various manures or fertilizers. Thus the 

 Dominion Botanist was able to prove that the organism of potato scab commonly 

 referred to as Oospora scabies, really belonged to the group of most widely-distributed 

 soil organisms of the genus Actinomyces. The biology of the soil is a study which 

 increases in importance every year, and, if followed by special research, will no doubt 

 lead to important discoveries in the control of many plant diseases which are carried 

 in tlie soil. The discover^' of relationship of the potato organism to the group of soil 

 organisms of the genus Actinomyces opens up a further field of inquiry, viz., its 

 relation to 'lump jaw' disease in cattle caused by another member of the same 

 group (AcUnomycus hovis). A number of diseases of the skin and hair of men 

 and animals, like ringworm, favus, etc., may be more closely related to this group 



